In order to assess the orientation dependence of device uniformity in GaAs integrated circuits, metal-semiconductor field-effect transistors (MESFET's) were fabricated along different crystal orientations on a 3-in. (100) substrate and compared with one another. Measurements indicated that the characteristics of FET's oriented along  and [011̄] directions have strong dependence upon their radial positions on the wafer. However, FET's oriented in  and  directions do not display such dependence and have better device uniformity. The orientation effect on the radial dependence of the FET device characteristics can be attributed to the piezoelectric effect.